1. Field of the Invention
The present invention relates to a semiconductor device having a pressure-contact type semiconductor element, preferably being a gate commutated turn-off (hereinafter referred to as GCT) thyristor element, in which most of the main current flowing between the anode and cathode during turn-on can be commutated to the gate electrode at the time of turn-off, and particularly to improvement for enhancing the resistance to vibration.
2. Description of the Background Art
Conventional GTO (Gate Turn-Off) thyristor devices have widely adopted structures in which the gate terminal connected to the gate electrode is drawn out in one direction to transmit a control signal to the gate electrode (see the technique described in Japanese Patent Application Laid-Open No. 56-125863 (1981), for example). In such a structure, however, large inductance is parasitically generated at the gate terminal and it is therefore difficult to instantaneously terminate the main current flowing from the anode to cathode when the element is turned off.
GCT thyristor devices in which this inductance is remarkably lowered have been developed to solve this problem. Such a GCT thyristor device adopts a ring-shaped gate terminal in place of the gate terminal extending in one direction; such a ring-shaped gate terminal is connected to a gate drive substrate on which a gate driver is provided. (See the techniques described in Japanese Patent Application Laid-Open No. 10-294406 (1998) and Japanese Patent Application Laid-Open No. 8-330572 (1996), for example). GCT thyristor devices adopting this structure can reduce the inductance of the loop including the GCT thyristor element, gate drive substrate and gate driver (referred to as gate-side inductance) to about {fraction (1/100)} of that of GTO thyristors.
The GCT thyristor devices thus having much lower gate-side inductance than GTO thyristors can increase the reverse gate current rise rate (diGQ/dt) during turn-off to about 100 times that of GTO thyristors, thus commutating almost all main current to the gate in a short time to be turned off. That is to say, the time required for turning off can be reduced and the turn-off gain can be almost one, thus achieving improved turn-off characteristics. This suppresses breakdown due to local heat generation in the semiconductor substrate and enables control of large current.
FIG. 38 is a top view showing a semiconductor device which is regarded not as a known technique but as a background art of the invention. This semiconductor device 200 is described in an U.S. application (application Ser. No. 09/549,062) by the same applicant. FIG. 39 shows the section of the semiconductor device taken along the line Bxe2x80x94B in FIG. 38. The semiconductor device 200 is constructed as a GCT thyristor device, which comprises a gate drive substrate 7 as a circuit board, a GCT thyristor 1 fixed on the gate drive substrate 7 and a gate driver as a control circuit including capacitors 36 and transistors 35. The transistors 35 are attached to the wall surface of wall-like members 34 fixed vertically on the gate drive substrate 7. While the capacitors 36 are arranged on the gate drive substrate 7, they are not shown in FIG. 39 for the sake of simplicity.
FIG. 40 shows the section of the semiconductor device taken along the line Axe2x80x94A in FIG. 38 and FIGS. 41 and 42 are sectional views each showing a part of FIG. 40 in an enlarged manner. The GCT thyristor element 1 comprises, in its center area, a disk-like semiconductor substrate (wafer) 24 having a pnpn structure inside and a gate region along the periphery, a cathode strain buffer plate 25 connected to the cathode region of the semiconductor substrate 24, and an anode strain buffer plate 26 connected to the anode region of the semiconductor substrate 24.
A cathode post electrode 2 as one main electrode is connected to the cathode strain buffer plate 25 and an anode post electrode 3 as the other main electrode is connected to the anode strain buffer plate 26. Further, an electrically conductive first cathode flange (main terminal plate) 14 is connected to the cathode post electrode 2 and a cathode fin electrode 5 is connected to the first cathode flange 14. An anode fin electrode 6 is connected to the anode post electrode 3. The semiconductor substrate 24, cathode strain buffer plate 25, anode strain buffer plate 26, cathode post electrode 2, anode post electrode 3 and first cathode flange 14 are sandwiched and pressed between the cathode fin electrode 5 and the anode fin electrode 6. Thus, the GCT thyristor element 1 is constructed as a kind of pressure-contact type semiconductor element.
In the semiconductor device 200, the part excluding the cathode fin electrode 5 and the anode fin electrode 6, i.e. the device part sandwiched with a pressing force between the pair of fin electrodes 5 and 6, is called a gate drive unit 300 (hereinafter refereed to as GDU). FIG. 38 shows the cathode fin electrode 5 with a broken line.
The GCT thyristor element 1 comprises a ring-shaped second cathode flange 20 fitted around the cathode post electrode 2 and a ring-shaped anode flange 23 fitted around the anode post electrode 3. An insulating tube 21 made of ceramics (e.g. alumina) is provided between the second cathode flange 20 and the anode flange 23. In FIG. 40, the unit composed of the semiconductor substrate 24, cathode strain buffer plate 25, anode strain buffer plate 26, cathode post electrode 2 and anode post electrode 3 passes through the insulating tube 21.
In the GCT thyristor element 1, as shown in FIGS. 41 and 42, a cathode electrode 7a forming a path of current between the gate driver and the cathode of the GCT thyristor element 1 and a gate electrode 7b forming a path of current between the gate driver and the gate of the GCT thyristor element 1 are both formed on one main surface of the gate drive substrate 7 (the main surface to which the cathode fin electrode 5 faces is referred to as xe2x80x9cupper main surfacexe2x80x9d hereinafter since this surface is shown as the upper surface in the drawings). The two are of course formed of circuit patterns insulated from each other. Although FIG. 38 does not show these circuit patterns for the sake of simplicity, the cathode electrode 7a is formed in a circuit pattern which is connected to branch-like protrusions of the first cathode flange 14 which will be described later and the gate electrode 7b is formed in a circuit pattern which is connected to branch-like protrusions of the gate flange (control terminal plate) 15 described later. The presence of the cathode electrode 7a and the gate electrode 7b forms a loop between the gate and cathode of the GCT thyristor element 1 and the gate driver. The gate current flows into this loop during commutation, whereby the main current flowing between the cathode and anode of the GCT thyristor element 1 is instantaneously terminated.
FIG. 43 is a perspective view showing the structure of the first cathode flange 14. The first cathode flange 14 is an electrically conductive thin plate having a thickness of about 0.2 to 2 mm, for example. As shown in FIG. 43, the first cathode flange 14 comprises a disk-like portion 14f having approximately the same diameter as the cathode post electrode 2, a flange portion 14e surrounding the disk-like portion 14f, and a plurality of branch-like protrusions 14d extending approximately outward from the flange portion 14e. This structure can be obtained by processing a thin plate with a press machine etc. The one-piece structure as shown in FIG. 43, i.e. the branch-like protrusions 14d , flange portion 14e and disk-like portion 14f integrally formed into the first cathode flange 14, can be easily obtained through a single press process.
Each branch-like protrusion 14d has a screw hole 14a near its end. Screws 9 are inserted in the screw holes 14a as shown in FIG. 41 to fix the branch-like protrusions 14d on the gate drive substrate 7. The gate drive substrate 7 has electrically conductive screw pedestals 17 at positions corresponding to the screw holes 14a; the branch-like protrusions 14d establish electric conduction with the cathode electrode 7a through the screw pedestals 17. The screw pedestals 17 can be attached to the gate drive substrate 7 by soldering, for example.
Commercially available low-price pedestal parts can be used as the screw pedestals 17. The screw pedestals 17 can work as long as they are in contact with the branch-like protrusions 14d and they do not have to provide a precisely smoothed surface like cathode spacer 4 and gate spacer 10 in a conventional gate commutated semiconductor device.
The branch-like protrusions 14d do not extend straight sideways from the flange portion 14e but they have some bends 14b and 14c so that the screw holes 14a can be positioned where the gate drive substrate 7 exists. The bends 14b allow a margin. Therefore vibrations and stresses generated during switching operation are absorbed especially at the bends 14b. 
In the semiconductor substrate 24, the gate region is formed on the cathode region side and a ring-shaped gate electrode 29 is connected to the gate region through a gate electrode connecting layer 28 as shown in FIGS. 41 and 42. The gate electrode 29 is connected to the gate flange 15 on its inner periphery side. The cathode strain buffer plate 25 is connected to the cathode region on the semiconductor substrate 24 through a cathode electrode connecting layer 27.
FIG. 44 shows the structure of the gate flange 15. The gate flange 15 is an electrically conductive thin plate having a thickness of about 0.2 to 2 mm, for example. As shown in FIG. 44, the gate flange 15 has a ring hole 15e in which the cathode post electrode 2 is inserted, a ring-shaped portion 15d surrounding the ring hole 15e, and a plurality of branch-like protrusions 15c extending approximately outward from the ring-shaped portion 15d. 
Each branch-like protrusion 15c has a screw hole 15a near its end. As shown in FIG. 42, screws 12 are inserted in the screw holes 15a to fix the branch-like protrusions 15c to the gate drive substrate 7. The gate drive substrate 7 has electrically conductive screw pedestals 16, like the screw pedestals 17, at the positions corresponding to the screw holes 15a; the branch-like protrusions 15c establish electric conduction with the gate electrode 7b through the screw pedestals 16. Like the screw pedestals 17, commercially available low-price pedestal parts can be used as the screw pedestals 16 and they can be attached to the gate drive substrate 7 by soldering, for example.
The branch-like protrusions 15c do not extend straight sideways from the ring-shaped portion 15d but they have bends 15b so that the screw holes 15a can be positioned where the gate drive substrate 7 exists. The bends 15b allow a margin. Therefore vibrations and stresses generated at the time of switching operation can be absorbed especially at the bends 15b. 
As shown in FIG. 42, an insulating sheet 30 is provided to achieve insulation of the gate electrode 29 and gate flange 15 from the cathode strain buffer plate 25 and cathode post electrode 2.
While the ring-shaped portion 15d of the gate flange 15 is sandwiched in the insulating tube 21, it projects outward from the side of the insulating tube 21. The branch-like protrusions 15c of the gate flange 15 extend outward from the insulating tube 21.
FIG. 38 shows, by way of example, a structure in which the first cathode flange 14 has six branch-like protrusions 14d and the gate flange 15 also has six branch-like protrusions 15c. The branch-like protrusions 14d and 15c are positioned to equally divide, into six, the periphery of the first cathode flange 14 and the gate flange 15, respectively. Further, the first cathode flange 14 and the gate flange 15 are arranged so that adjacent branch-like protrusions 14d and 15c extend approximately parallel with each other and so that the branch-like protrusions 14d and 15c are alternately positioned. The distance between the branch-like protrusions 14d and 15c is designed to be equal to or larger than the minimum limit which can ensure insulation.
Further, when the structure is designed so that the branch-like protrusions 14d and 15c are sufficiently separated from the cathode fin electrode 5 and the anode fin electrode 6, it is possible to suppress the possibility of leakage current from external circuitry connected to the cathode fin electrode 5 or the anode fin electrode 6 to the branch-like protrusions 14d and 15c. For this purpose, the bends 14b, 14c and 15b of the branch-like protrusions 14d and 15c can be adjusted to determine the relative position between the gate drive substrate 7 and the GCT thyristor element 1 in the height direction.
It is desired that the first cathode flange 14 and the gate flange 15 should have a plurality of, three or more, branch-like protrusions 14d and branch-like protrusions 15c, respectively. If they have only one branch-like protrusion each, there will be a difficulty in holding the GCT thyristor element 1. Further, it does not make much difference in characteristics from the gate terminal extending in one direction as adopted in conventionally known GTO thyristors. When they have two branch-like protrusions each, the GCT thyristor element 1 will be resonated or twisted by vibrations and stresses generated during switching operation. With a structure having three branch-like protrusions 14d and three branch-like protrusions 15c, the three can be formed in positions approximately equally dividing, into three, the periphery of the first cathode flange 14 and the gate flange 15 so that the GCT thyristor element 1 will not be resonated nor twisted by vibrations and stresses generated during switching operation.
The number of branch-like protrusions can be selected in the range of three or more by considering the current capacity of the GCT thyristor element 1, or the turn-off reverse gate current rise rate (diGQ/dt) required for the GCT thyristor element 1, required inductance value, working efficiency in manufacturing process, cost, etc.
With the semiconductor device 200 thus constructed, the gate flange 15 and the first cathode flange 14 can be fixed to the gate drive substrate 7 by using low-price pedestal parts, instead of the cathode spacer and gate spacer used in conventionally-known GCT thyristor devices, so as to achieve cost reduction. This structure also achieves weight reduction of the semiconductor device 200.
Moreover, while screws are attached on both upper and lower surfaces of the gate drive substrate in conventionally known GCT thyristor devices, the branch-like protrusions 14d of the first cathode flange 14 and the branch-like protrusions 15c of the gate flange 15 are fixed with screws on the same surface of the gate drive substrate 7, which provides improved working efficiency in manufacture process and maintenance.
Furthermore, while interconnection patterns are formed on both upper and lower surfaces (i.e. both of one main surface and the other main surface) of the gate drive substrate 7 in conventionally known GCT thyristor devices, the gate and cathode interconnection patterns of this device are both formed on the upper main surface of the gate drive substrate 7, which reduces the time and cost required for manufacture.
On the other hand, the semiconductor device 200 does not have a case like those of conventionally known GCT thyristor devices, which may result in lack of strength. Reinforcing members 18 are therefore provided as shown in FIGS. 38 and 39 in order to enhance the strength. In FIG. 39, a pair of L-shaped reinforcing members 18 are provided parallel with each other on opposite sides of the GCT thyristor element 1. Each reinforcing member 18 has a flat portion 41 extending parallel with the upper main surface of the gate drive substrate 7 and an upright portion 40 connected to one end of it and vertically standing above the upper main surface of the gate drive substrate 7.
The reinforcing members 18 are fixed on the gate drive substrate 7 with screws 33 and nuts 32, each reinforcing member 18 being insulated from the gate drive substrate 7 by insulating spacers 37 provided in two positions separated along the direction in which the flat portions 41 extend. The spacers 37 interposed between respective flat portions 41 and the upper main surface of the gate drive substrate 7 serve also to keep the interval between them. The reinforcing members 18 thus effectively function as reinforcing members for preventing the gate drive substrate 7 from curving due to the weight of the transistors 35 etc.
The upright portions 40 are each detachably fixed with a screw 31 to a side wall of the cathode fin electrode 5 which is formed in an approximately rectangular shape in plane view. Fixing the cathode fin electrode 5 to the reinforcing members 18 in this way more effectively prevents the gate drive substrate 7 from curving because of the weight of the transistors 35 etc.
In the semiconductor device 200, as described above, the flanges 14 and 15 provided in the GCT thyristor element 1 are just flexibly connected to the GDU 300, so that they do not substantially function as members for supporting the GDU 300. The GDU 300 is supported on the GCT thyristor element 1 mostly by the reinforcing members 18 provided on the gate drive substrate 7. Thus, the gate drive substrate 7 is supported on the cathode fin electrode 5 substantially at the two supporting points in the pair of upright portions 40 of the pair of reinforcing members 18.
Accordingly, when the semiconductor device 200 is used in an environment where it is subjected to vibrations, e.g. when it is applied to an electric railway train etc., and particularly when vibrations are applied to the semiconductor device 200 in the direction vertical to the main surface of the gate drive substrate 7 (Z direction), moments are produced around the two supporting points in the pair of upright portions 40 of the pair of reinforcing members 18 to possibly cause the GDU 300 to resonate.
The present invention has been made to solve the above-described problem of the background art and an object of the present invention is to provide a semiconductor device which can suppress resonance phenomena in an environment where it is subjected to vibrations.
According to a first aspect of the present invention, a semiconductor device comprises: (a) a circuit board having a pair of main surfaces and an opening selectively formed through the pair of main surfaces; (b) a pressure-contact type semiconductor element inserted in the opening, the pressure-contact type semiconductor element comprising a semiconductor substrate, a pair of main electrodes between which opposite main surfaces of the semiconductor substrate are sandwiched, a fin electrode abutting on one of the pair of main electrodes and facing one main surface of the pair of main surfaces of the circuit board, and a control terminal connected to the semiconductor substrate; (c) a control circuit attached to the circuit board and electrically connected to the control terminal to control the pressure-contact type semiconductor element; and (d) a supporting member for supporting the circuit board on the fin electrode at three or more supporting points arranged to surround the opening.
Preferably, according to a second aspect, in the semiconductor device, the supporting member comprises (d-1) a pair of reinforcing members having a pair of flat portions arranged to extend in one direction along the periphery of the opening, while facing the said one main surface in a pair of positions facing each other across the opening, and a pair of upright portions respectively coupled to the pair of flat portions at one end in the said one direction, the pair of upright portions vertically standing above the said one main surface and detachably fixed on a side wall surface of the fin electrode, (d-2) a spacer interposed between the pair of flat portions and the said one main surface to fixedly couple the pair of flat portions and the circuit board at an interval therebetween, the spacer being arranged, for each flat portion, in a position including at least two points spaced from each other along the said one direction, and (d-3) a fixing member provided in such a position as to surround the opening together with the pair of upright portions and interposed between the fin electrode and the said one main surface to detachably fix the fin electrode and the circuit board at an interval therebetween.
Preferably, according to a third aspect, in the semiconductor device, the supporting member comprises (d-1) a pair of reinforcing members interposed between the fin electrode and the one main surface in a pair of positions facing each other across the opening, the pair of reinforcing members extending in one direction along the periphery of the opening and detachably fixed along the one direction in close contact on a surface of the fin electrode which faces the one main surface, and (d-2) a spacer interposed between the pair of reinforcing members and the one main surface to fixedly couple the pair of reinforcing members and the circuit board at an interval therebetween, the spacer being arranged, for each reinforcing member, in a position including at least two points spaced from each other along the one direction.
Preferably, according to a fourth aspect, in the semiconductor device, the supporting member comprises (d-1) a pair of reinforcing members having a pair of flat portions arranged to extend in one direction along the periphery of the opening, while facing the one main surface in a pair of positions facing each other across the opening, a pair of upright portions respectively coupled to the pair of flat portions at one end in one direction, the pair of upright portions vertically standing above the one main surface and detachably fixed on a side wall surface of the fin electrode, and a pair of fixing portions respectively coupled to the pair of flat portions at the other end in the one direction and detachably fixed to the fin electrode, and (d-2) a spacer interposed between the pair of flat portions and the one main surface to fixedly couple the pair of flat portions and the circuit board at an interval therebetween, the spacer being arranged, for each flat portion, in a position including at least two points spaced from each other along the one direction.
According to a fifth aspect, a semiconductor device comprises: (a) a circuit board having a pair of main surfaces and an opening selectively formed through the pair of main surfaces; (b) a pressure-contact type semiconductor element inserted in the opening, the pressure-contact type semiconductor element comprising a semiconductor substrate, a pair of main electrodes between which opposite main surfaces of the semiconductor substrate are sandwiched, a fin electrode abutting on one of the pair of main electrodes and facing one main surface of the pair of main surfaces of the circuit board, and a control terminal connected to the semiconductor substrate; (c) a control circuit attached to the circuit board and electrically connected to the control terminal to control the pressure-contact type semiconductor element; (d) a reinforcing member having a plate-like flat portion arranged to cover an area surrounding the opening in the one main surface, and an upright portion coupled to one end of the flat portion in one direction along the one main surface, the upright portion standing vertically above the one main surface and detachably fixed on a side wall surface of the fin electrode; and (e) a spacer interposed between the flat portion and the one main surface to fixedly couple the flat portion and the circuit board at an interval therebetween, the spacer being arranged in a position including at least four points separated from one another to surround the opening.
According to a sixth aspect, a semiconductor device comprises: (a) a circuit board having a pair of main surfaces and an opening selectively formed through the pair of main surfaces; (b) a pressure-contact type semiconductor element inserted in the opening, the pressure-contact type semiconductor element comprising a semiconductor substrate, a pair of main electrodes between which opposite main surfaces of the semiconductor substrate are sandwiched, a fin electrode abutting on one of the pair of main electrodes and facing one main surface of the pair of main surfaces of the circuit board, and a control terminal connected to the semiconductor substrate; (c) a control circuit attached to the circuit board and electrically connected to the control terminal to control the pressure-contact type semiconductor element; (d) a pair of reinforcing members having a pair of flat portions arranged to extend in one direction along the periphery of the opening, while facing the one main surface in a pair of positions facing each other across the opening, and a pair of upright portions respectively coupled to the pair of flat portions at one end in the one direction, the pair of upright portions vertically standing above the one main surface and detachably fixed on a side wall surface of the fin electrode; and (e) a spacer interposed between the pair of flat portions and the one main surface to fixedly couple the pair of flat portions and the circuit board at an interval therebetween, the spacer being arranged, for each flat portion in a separated manner, in three or more positions arranged along the one direction.
According to a seventh aspect, a semiconductor device comprises: (a) a circuit board having a pair of main surfaces and an opening selectively formed through the pair of main surfaces; (b) a pressure-contact type semiconductor element inserted in the opening, the pressure-contact type semiconductor element comprising a semiconductor substrate, a pair of main electrodes between which opposite main surfaces of the semiconductor substrate are sandwiched, a fin electrode abutting on one of the pair of main electrodes and facing one main surface of the pair of main surfaces of the circuit board, and a control terminal connected to the semiconductor substrate; (c) a control circuit attached to the circuit board and electrically connected to the control terminal to control the pressure-contact type semiconductor element; (d) a pair of reinforcing members having a pair of flat portions arranged to extend in one direction along the periphery of the opening, while facing the one main surface in a pair of positions facing each other across the opening, and a pair of upright portions respectively coupled to the pair of flat portions at one end in the one direction, the pair of upright portions vertically standing above the one main surface and detachably fixed on a side wall surface of the fin electrode; and (e) a spacer interposed between the pair of flat portions and the one main surface to fixedly couple the pair of flat portions and the circuit board at an interval therebetween, the spacer being arranged, for each flat portion, to extend along the one direction in close contact with each flat portion and the one main surface along the one direction.
According to an eighth aspect, a semiconductor device comprises: (a) a circuit board having a pair of main surfaces and an opening selectively formed through the pair of main surfaces; (b) a pressure-contact type semiconductor element inserted in the opening, the pressure-contact type semiconductor element comprising a semiconductor substrate, a pair of main electrodes between which opposite main surfaces of the semiconductor substrate are sandwiched, a fin electrode abutting on one of the pair of main electrodes and facing one main surface of the pair of main surfaces of the circuit board, and a control terminal connected to the semiconductor substrate; (c) a control circuit attached to the circuit board and electrically connected to the control terminal to control the pressure-contact type semiconductor element; (d) a pair of reinforcing members having a pair of flat portions arranged to extend in one direction along the periphery of the opening, while facing the one main surface in a pair of positions facing each other across the opening, the pair of flat portions having a plurality of through holes arranged along the one direction, and a pair of upright portions respectively coupled to the pair of flat portions at one end in the one direction, the pair of upright portions vertically standing above the one main surface and detachably fixed on a side wall surface of the fin electrode; and (e) a spacer interposed between the pair of flat portions and the one main surface to fixedly couple the pair of flat portions and the circuit board at an interval therebetween, the spacer being arranged, for each flat portion, in a position including at least two points spaced from each other along the one direction.
According to a ninth aspect, a semiconductor device comprises: (a) a circuit board having a pair of main surfaces and an opening selectively formed through the pair of main surfaces; (b) a pressure-contact type semiconductor element inserted in the opening, the pressure-contact type semiconductor element comprising a semiconductor substrate, a pair of main electrodes between which opposite main surfaces of the semiconductor substrate are sandwiched, a fin electrode abutting on one of the pair of main electrodes and facing one main surface of the pair of main surfaces of the circuit board, and a control terminal connected to the semiconductor substrate; (c) a control circuit attached to the circuit board and electrically connected to the control terminal to control the pressure-contact type semiconductor element; (d) a pair of reinforcing members having a pair of flat portions arranged to extend in one direction along the periphery of the opening, while facing the one main surface in a pair of positions facing each other across the opening, and a pair of upright portions respectively coupled to the pair of flat portions at one end in the one direction, the pair of upright portions vertically standing above the one main surface and detachably fixed on a side wall surface of the fin electrode; (e) a spacer interposed between the pair of flat portions and the one main surface to fixedly couple the pair of flat portions and the circuit board at an interval therebetween, the spacer being arranged, for each flat portion, in a position including at least two points spaced from each other along the one direction; and (f) a frame fixed to the circuit board along at least part of the periphery of the circuit board and in close contact with the at least part of the periphery.
Preferably, according to a tenth aspect, in the semiconductor device, the supporting member comprises (d-1) a spacer interposed between the fin electrode and the one main surface in four or more positions separated to surround the opening to detachably and fixedly couple the fin electrode and the circuit board at an interval therebetween.
According to an eleventh aspect, a semiconductor device comprises: (a) a circuit board having a pair of main surfaces and an opening selectively formed through the pair of main surfaces; (b) a pressure-contact type semiconductor element inserted in the opening, the pressure-contact type semiconductor element comprising a semiconductor substrate, a pair of main electrodes between which opposite main surfaces of the semiconductor substrate are sandwiched, a fin electrode abutting on one of the pair of main electrodes and facing one main surface of the pair of main surfaces of the circuit board, and a control terminal connected to the semiconductor substrate; (c) a control circuit attached to the circuit board and electrically connected to the control terminal to control the pressure-contact type semiconductor element; (d) a pair of reinforcing members having a pair of flat portions arranged to extend in one direction along the periphery of the opening, while facing the one main surface in a pair of positions facing each other across the opening, and a pair of upright portions respectively coupled to the pair of flat portions at one end in the one direction, the pair of upright portions vertically standing above the one main surface and detachably fixed on a side wall surface of the fin electrode; (e) a spacer interposed between the pair of flat portions and the one main surface to fixedly couple the pair of flat portions and the circuit board at an interval therebetween, the spacer being arranged, for each flat portion, in a position including at least two points spaced from each other along the one direction; (f) another reinforcing member having another plate-like flat portion arranged to face an area of the one main surface which does not face the fin electrode, and another upright portion coupled to one end of said another flat portion in one direction along the one main surface, said another upright portion vertically standing above the one main surface and detachably fixed on the side wall surface of the fin electrode; and (g) another spacer interposed between said another flat portion and the one main surface and fixedly coupling said another flat portion and the circuit board at an interval therebetween, said another spacer being arranged in a position including at least four points separated from one another and not aligned in a straight line.
According to a twelfth aspect, a semiconductor device comprises: (a) a circuit board having a pair of main surfaces and an opening selectively formed through the pair of main surfaces; (b) a pressure-contact type semiconductor element inserted in the opening, the pressure-contact type semiconductor element comprising a semiconductor substrate, a pair of main electrodes between which opposite main surfaces of the semiconductor substrate are sandwiched, a fin electrode abutting on one of the pair of main electrodes and facing one main surface of the pair of main surfaces of the circuit board, another fin electrode abutting on the other one of the pair of main electrodes and facing the other main surface of the pair of main surfaces of the circuit board, and a control terminal connected to the semiconductor substrate; (c) a control circuit attached to the circuit board and electrically connected to the control terminal to control the pressure-contact type semiconductor element; (d) a ring-shaped elastic member sandwiched with a pressing force between said fin electrode and said one main surface and surrounding the opening; and (e) another ring-shaped elastic member sandwiched with a pressing force between said another fin electrode and said other main surface and surrounding the opening.
Preferably, according to a thirteenth aspect, in the semiconductor device, the fixing member comprises (d-3-1) a spacer having a projection projecting to a side opposite to the one end along the one direction, the spacer being fixed on the circuit board and abutting on a surface of the fin electrode which faces the one main surface to hold the interval between the fin electrode and the circuit board, and (d-3-2) an engaging member fixed to the fin electrode and detachably engaged with the projection with an elastic recovery force to press the projection against the fin electrode.
Preferably, according to a fourteenth aspect, in the semiconductor device, the supporting member further comprises (d-3) a pair of engaging members fixed to the fin electrode and engaged slidably in the one direction with the pair of reinforcing members with an elastic recovery force to press the pair of reinforcing members against the fin electrode, and the pair of reinforcing members are fixed by the pair of engaging members in close contact on the surface of the fin electrode which faces the one main surface.
Preferably, according to a fifteenth aspect, in the semiconductor device, the pair of fixing portions comprise a pair of protrusions vertically standing above the one main surface and detachably fixed on another side wall surface of the fin electrode which is opposite to the side wall surface.
Preferably, according to a sixteenth aspect, in the semiconductor device, the pair of fixing portions are fastened with screws and thus detachably coupled respectively to the pair of flat portions.
Preferably, according to a seventeenth aspect, in the semiconductor device, the pair of upright portions and the pair of fixing portions are integrally coupled respectively to the pair of flat portions.
Preferably, according to an eighteenth aspect, in the semiconductor device, the pair of fixing portions are fastened with screws and thus detachably fixed to said another side wall surface.
Preferably, according to a nineteenth aspect, in the semiconductor device, each of the pair of fixing portions comprises a protrusion abutting on a surface of the fin electrode which faces the one main surface and protruding along the one direction to a side opposite to said one end, and the supporting member further comprises (d-3) an engaging member fixed on the fin electrode and detachably engaged with the protrusions to hold the protrusions abutting on the surface of the fin electrode which faces the one main surface.
Preferably, according to a twentieth aspect, in the semiconductor device, the fin electrode has a recess on its another side wall surface which is opposite to said side wall surface and the pair of fixing portions respectively have a pair of protrusions which can be inserted in the recess, and wherein the pair of protrusions are detachably inserted in the recess to fix the pair of fixing portions to the fin electrode.
Preferably, according to a twenty-first aspect, the semiconductor device further comprises (f) a ring-shaped elastic member sandwiched with a pressing force between the flat portion and the one main surface to surround the opening.
Preferably, according to a twenty-second aspect, in the semiconductor device, the fin electrode has a fin on its said side wall surface and said another upright portion has a window selectively opening in a part facing toward the fin.
Preferably, according to a twenty-third aspect, in the semiconductor device, the pair of upright portions are fastened with screws and thus detachably fixed to the side wall surface of the fin electrode.
Preferably, according to a twenty-fourth aspect, in the semiconductor device, the upright portion is fastened with a screw and thus detachably fixed to the side wall surface of the fin electrode.
Preferably, according to a twenty-fifth aspect, in the semiconductor device, the one direction is a direction approximately connecting the center of the opening and the center of the one main surface, and while the pair of flat portions have two ends in the one direction, the one end at which the pair of upright portions are coupled is the end closer to the center of the one main surface.
Preferably, according to a twenty-sixth aspect, in the semiconductor device, the one direction is a direction approximately connecting the center of the opening and the center of the one main surface, and while the flat portion has two ends in the one direction, the one end at which the upright portion is coupled is the end closer to the center of the one main surface.
Preferably, according to a twenty-seventh aspect, in the semiconductor device, for each flat portion, the spacer is arranged in a separated manner in three or more positions arranged along the one direction.
Preferably, according to a twenty-eighth aspect, in the semiconductor device, for each flat portion, the spacer extends along the one direction in close contact with each flat portion and the one main surface along the one direction.
Preferably, according to a twenty-ninth aspect, the semiconductor device further comprises a frame fixed to the circuit board along at least part of the periphery of the circuit board and in close contact with the at least part of the periphery.
Preferably, according to a thirtieth aspect, in the semiconductor device, the circuit board has a contour having opposite two sides in plane view and the at least part of the periphery of the circuit board corresponds to the two sides.
Preferably, according to a thirty-first aspect, in the semiconductor device, the circuit board has first and second interconnection patterns respectively provided on the one main surface and the other main surface, the pressure-contact type semiconductor element further comprises a main terminal plate, the main terminal plate having its inner region electrically connected to the one main electrode, the main terminal plate having a ring-shaped region extending outside of the inner region along its periphery, the ring-shaped region of the main terminal plate being connected to the first interconnection pattern in a part disposed in a ring-shaped region extending along the periphery of the opening, and wherein the control circuit is electrically connected to the main terminal plate as well as the control terminal to control the pressure-contact type semiconductor element, and wherein the control terminal is a control terminal plate having its inner region electrically connected to the semiconductor substrate, the control terminal plate having a ring-shaped region extending outside of the inner region along its periphery, the ring-shaped region of the control terminal plate being connected to the second interconnection pattern in a part disposed in a ring-shaped region extending along the periphery of the opening.
Preferably, according to a thirty-second aspect, in the semiconductor device, the circuit board has first and second interconnection patterns provided on the one main surface, the pressure-contact type semiconductor element further comprises a main terminal plate, the main terminal plate having its inner region electrically connected to the one main electrode, the main terminal plate having a branch-like protrusion projecting outward from the inner region, the branch-like protrusion of the main terminal plate being connected to the first interconnection pattern in a part disposed in the vicinity of the periphery of the opening, and the control circuit is electrically connected to the main terminal plate as well as the control terminal to control the pressure-contact type semiconductor element, and wherein the control terminal is a control terminal plate having its inner region electrically connected to the semiconductor substrate, the control terminal plate having a branch-like protrusion projecting outward from the inner region, the branch-like protrusion of the control terminal plate being connected to the second interconnection pattern in a part disposed in the vicinity of the periphery of the opening.
Preferably, according to a thirty-third aspect, in the semiconductor device, the main terminal plate and the control terminal plate are fastened with screws to the circuit board.
Preferably, according to a thirty-fourth aspect, in the semiconductor device, the pressure-contact type semiconductor element is a gate commutated turn-off thyristor element.
According to the first aspect, a circuit board connected to a pressure-contact type semiconductor element is stably supported on a fin electrode without freedom of rotation at three or more supporting points arranged to surround an opening in which the pressure-contact type semiconductor element is inserted. Thus no rotating moment is produced around each supporting point even in an environment in which the semiconductor device is subjected to vibrations and the resonance phenomenon of the circuit board is thus prevented. Thus, a semiconductor device having excellent vibration resistance is obtained.
According to the second aspect, a pair of reinforcing members and a spacer enhance the rigidity of the circuit board (including components provided thereon) to further suppress the resonance phenomenon. Moreover, since the upright portions of the reinforcing members are detachably fixed on a side wall surface of the fin electrode, inserting attachment can be used in the process of assembling the semiconductor device.
According to the third aspect, a pair of reinforcing members and a spacer enhance the rigidity of the circuit board to further suppress the resonance phenomenon. Moreover, the pair of reinforcing members are detachably fixed in close contact on the surface of the fin electrode which faces the circuit board, which means that the supporting points are continuously and infinitely distributed. This further enhances the effect of suppressing the resonance phenomenon.
According to the fourth aspect, a pair of reinforcing members and a spacer enhance the rigidity of the circuit board to further suppress the resonance phenomenon. Moreover, the device can be manufactured at low cost since the four supporting points for effectively suppressing the resonance phenomenon can be realized just by adding a pair of fixing members to the pair of reinforcing members.
According to the fifth aspect, a reinforcing member and spacer enhance the rigidity of the circuit board to suppress the resonance phenomenon. Particularly, the rigidity is effectively enhanced since the reinforcing member has a plate-like flat portion arranged to cover an area surrounding the opening.
According to the sixth aspect, a pair of reinforcing members and a spacer enhance the rigidity of the circuit board to suppress the resonance phenomenon. Particularly, the spacer is arranged in a separated manner in three or more positions for each reinforcing member, which effectively enhances the rigidity of the circuit board and achieves weight reduction of the circuit board (including components provided thereon). This more effectively suppresses the resonance phenomenon.
According to the seventh aspect, a pair of reinforcing members and a spacer enhance the rigidity of the circuit board to suppress the resonance phenomenon. Particularly, the rigidity of the circuit board is effectively enhanced since the spacer is provided to extend along each reinforcing member and in close contact with each reinforcing member and the circuit board. This more effectively suppresses the resonance phenomenon.
According to the eighth aspect, a pair of reinforcing members and a spacer enhance the rigidity of the circuit board to suppress the resonance phenomenon. Further, inserting attachment can be used in the process of assembling the semiconductor device since upright portions of the reinforcing members are detachably fixed on a side wall surface of the fin electrode. Moreover, the weight of the circuit board including components provided thereon can be reduced since the reinforcing members have a plurality of through holes arranged along the direction in which they extend. This further effectively suppresses the resonance phenomenon.
According to the ninth aspect, a frame is fixed to the circuit board along at least part of the periphery of the circuit board and in contact with at least that part, so as to enhance the rigidity of the circuit board. This suppresses the resonance phenomenon of the circuit board.
According to the tenth aspect, a spacer supporting at at least four supporting points further suppresses the resonance phenomenon. Moreover, the device can be manufactured with a smaller number of parts and hence at lower cost.
According to the eleventh aspect, a pair of reinforcing members and a spacer enhance the rigidity of the circuit board to suppress the resonance phenomenon. Furthermore, another reinforcing member and another spacer further enhance the rigidity of the circuit board to further effectively suppress the resonance phenomenon. Moreover, a pair of upright portions of the pair of reinforcing members and an upright portion of the other reinforcing member are detachably fixed on a side wall surface of the fin electrode, so that the inserting attachment can be used in the process of assembling the semiconductor device.
According to the twelfth aspect, a pair of ring-shaped elastic members are sandwiched between the pair of fin electrodes and the circuit board to suppress the resonance phenomenon of the circuit board.
According to the thirteenth aspect, a projection projecting away from the upright portions of the reinforcing members and an engaging member engaged with the projection with an elastic recovery force serve as the third supporting point to support the circuit board on the fin electrode. This structure further facilitates the inserting attachment in the semiconductor device assembly process, thus improving the assembly efficiency and reducing the assembly cost.
According to the fourteenth aspect, a pair of engaging members slidably engage with the pair of reinforcing members with an elastic recovery force to fix the pair of reinforcing members on the fin electrode, which facilitates the inserting attachment in the semiconductor device assembly process. This improves the assembly efficiency and reduces the assembly cost.
According to the fifteenth aspect, the pair of upright portions and a pair of similar protrusions detachably fix the pair of reinforcing members on a pair of opposite side wall surfaces of the fin electrode and the pair of reinforcing members can thus be easily fixed on the fin electrode.
According to the sixteenth aspect, the pair of fixing portions are fastened with screws and thus detachably coupled to the pair of flat portions and therefore the inserting attachment can be used in the semiconductor device assembly process.
According to the seventeenth aspect, the pair of upright portions and the pair of fixing portions are integrated with the pair of flat portions, so that the stacking attachment can be used in the semiconductor device assembly process. Further, integrally forming each reinforcing member as one piece reduces the number of parts and reduces the manufacturing cost.
According to the eighteenth aspect, the pair of fixing portions are fastened with screws and thus detachably fixed on a side wall surface of the fin electrode, which further facilitates the process of assembling the semiconductor device. This improves the assembly efficiency and reduces the assembly cost.
According to the nineteenth aspect, a pair of protrusions projecting away from the pair of upright portions and a pair of engaging members detachably engaged with the protrusions serve as the third and fourth supporting points to support the circuit board on the fin electrode. This further facilitates the inserting attachment in the semiconductor device assembly process, thus improving the assembly efficiency and reducing the assembly cost.
According to the twentieth aspect, a pair of protrusions are inserted in a recess formed on the fin electrode and serve as the third and fourth supporting points to support the circuit board on the fin electrode. Therefore the stacking attachment can be easily achieved in the process of assembling the semiconductor device, and the assembly efficiency is enhanced and the assembly cost is reduced.
According to the twenty-first aspect, a ring-shaped elastic member is sandwiched between the flat portion of the reinforcing member and the circuit board to further effectively suppress the resonance phenomenon of the circuit board.
According to the twenty-second aspect, the fin electrode has a fin and the upright portion of another reinforcing member has a window opening over the fin, which allows the fin electrode to effectively dissipate heat.
According to the twenty-third aspect, the pair of upright portions are fastened with screws and thus detachably fixed on a side wall surface of the fin electrode, which facilitates the semiconductor device assembly process. This improves the assembly efficiency and reduces the assembly cost.
According to the twenty-fourth aspect, the upright portion is fastened with screws and thus detachably fixed on a side wall surface of the fin electrode, which facilitates the semiconductor device assembly process. This improves the assembly efficiency and reduces the assembly cost.
According to the twenty-fifth aspect, the pair of upright portions are located closer to the center of the circuit board, which reduces moments produced by vibrations around the pair of upright portions. This more effectively suppresses the resonance phenomenon.
According to the twenty-sixth aspect, the upright portion is located closer to the center of the circuit board, which reduces moments produced by vibrations around the upright portion. This further effectively suppresses the resonance phenomenon.
According to the twenty-seventh aspect, the spacer is provided in a separated manner in three or more points for each reinforcing member, so that the rigidity of the circuit board is effectively enhanced while achieving weight reduction of the circuit board. This more effectively suppresses the resonance phenomenon.
According to the twenty-eighth aspect, the spacer is provided to extend along each reinforcing member in close contact with each reinforcing member and the circuit board, thus effectively enhancing the rigidity of the circuit board. This further effectively suppresses the resonance phenomenon.
According to the twenty-ninth aspect, a frame is fixed to the circuit board along at least part of the periphery of the circuit board and in contact with that part, so as to enhance the rigidity of the circuit board. This further effectively suppresses the resonance phenomenon of the circuit board.
According to the thirtieth aspect, the frame is fixed to the circuit board in close contact with opposite two sides of the circuit board, thus further enhancing the rigidity of the circuit board. This further effectively suppresses the resonance phenomenon of the circuit board.
According to the thirty-first aspect, the main terminal plate and the control terminal plate are connected to the interconnection patterns in a ring-shaped area extending along the periphery of the opening of the circuit board. This suppresses the inductance between the control circuit and the semiconductor substrate and enhances operating speed of the pressure-contact type semiconductor element. The structure is therefore suitable for use with a gate commutated turn-off element.
According to the thirty-second aspect, the main terminal plate and the control terminal plate are both connected to interconnection patterns provided on one main surface of the circuit board, which facilitates the assembly process of the semiconductor device. This improves the assembly efficiency and saves the assembly cost.
According to the thirty-third aspect, the main terminal plate and the control terminal plate are fastened with screws to the circuit board, which further facilitates the process of assembling the semiconductor device. This further improves the assembly efficiency and further saves the assembly cost.
According to the thirty-fourth aspect, the pressure-contact type semiconductor element is a gate commutated turn-off thyristor element and the turn-off characteristic can be improved. This suppresses excessive local heat generation in the semiconductor substrate and the structure is suitable for application controlling large current.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.